The invention relates to a concrete-molding machine having a ram and having an upper mold part, which two parts can be clamped together in a vibration-resistant manner with the aid of pneumatic lifting elements.
A concrete-molding machine of this type is known from German Utility Model 88 15 262. According to the latter, the connecting members are configured as tie rods which hang down from the ram, have a wide head at the bottom and can be drawn upwards to the ram by means of individual pneumatic lifting elements. Formed in the abutment plate of the upper die part are a plurality of mutually parallel slots into which the shanks of the tie members can be inserted, In order to attach such an upper mold part, the latter is guided laterally in the horizontal direction into the tie rods, that is to say is suspended thereon, with the result that the bearing plate, and thus the entire upper mold part, bears with its weight on the heads of the tie rods. The pneumatic lifting elements then draw the upper mold part up to the ram, via the tie rods, until it rests firmly against the ram.
This known arrangement, also designated as a quick-change device, has two fundamental disadvantages. The long slots in the abutment plate of the upper mold part require a comparatively complicated substructure, which produces a free channel beneath the slots, through which channel the heads of the tie rods can be moved. On the other hand, the lateral extension and retraction of the upper mold part is unsatisfactory. This is usually carried out by the stacker truck, the accuracy of the movement control leaving something to be desired, which, on the other hand, has resulted in the tie rods being selected to be longer and larger, and the slots being selected to be wider, than they would have to be merely from strength aspects.